Electric-furnace terminal.



E. G. SPEIDEN.

ELECTRIC FURNACE TERMINAL.

APPLICATION FILED mm: 17, 1909.

935,939. Patented 0ct.5,1909.

2 SHEETS-SHEET 1.

Smvenkoz 6am 4 Q/vihsuozo E. G. SPEIDEN.

ELEGTRIG FURNACE TERMINAL. APPLIOATION FILED JUNE 17, 1909.

Patented 001;. 5, 1909.

2 SHEETS-8HEET 2.

UNITED sT rEs PATENT onrion.

EBEN C. SPEIDEN, OF NIAGARA FALLS, NEW YORK, ASSIGNOR T0 INTERNATIONAL ACHESON GRAPHITE COMPANY, OF NIAGARA FALLS, NEW YORK, A COBPORATIO OF NEW JERSEY.

ELECTRIC-FURNACE TERMINAL.

Specification of Letters Patent.

Patented net. 5, to.

To all whom it may concern:

Be it known that I, EBEN G. SPEIDEN, a citizen of the United States, residing at Niagara Falls, in the county of Niagara and State of New ,York, have invented certain new and useful Improvements in Electric- Furnace- Terminals, of which the following is a specification.- i

The object of this invention vis the provision in an electric furnace of means for reducing the heat losses through the electrodes, said means also adapted, in certain embodiments of the invention, to efiect a proper distribution of current between the charge and terminal of an electric furnace;

The invention, while capable of use in various relations, is particularly advantageous in connection with furnaces of the resistance type having fixed terminals, such for example as the furnaces employed for the production of graphite, graphite articles, silicid of carbon, etc.

The invention will be described by reference to furnaces of this character, it being however pointed out that it is not restricted to this particular application.

For a full understanding ofthe invention reference is made to .the accompanying drawing, illustrating certain embodiments thereof, i l

In said drawings :Figure 1 is a vertical sectional View through one end of a furnace having a terminal embodying the invention; Fig. 2 is a plan view of one form of extension head; and Fig. 3 is a vertical section of the same on line 2.2 of F ig. 2,

In furnaces having terminals of relatively largecross-section and employing currents of very high amperage, the terminals become highly heated and conduct considerable quantities of heat from the adjacent portion of'the charge, this resulting not only in a Waste of heat and therefore of current, but at times in the injury of the outer or exposed portion of the terminal by oxfilation. Aca cording to the present invention such losses are reduced by providing in the current path a zone or section of comparatively low heatconductivity, whereby an obstruction is offered to the flow of heat from the furnace. This obstruction may comprise merely a joint or imperfect contact, a section of reduced cross-sectional area, or preferably a filling or mass interp5ed in the current path through the electrode or terminal and con-' sisting of' a material of suitable electrical conductivity but of low heat conductivity as compared with the material of which the terminal is' composed, which in practice is usually graphite. A suitable filling material for most purposes consists of carbon or graphite in subdivided form. In certain cases the filling may be agglomerated into a solid mass by meansof a suitable binder, as a hydrocarbon, pitch, tar, molasses, etc.

One mode of assembly of bars into a fixed terminal is shown in Fig. 1, wherein 1 represents a terminal composed of carbon or graphite members 2, the interior members being transversely divided either wholly or in part as indicated at 3. The several members 2 are laterally in conductive relation and are preferably laid in a highly conductive graphitic paste filling the joints 4, 5-

represents the metallic connection to the bus-bars at the outer end of the terminal.

through the exterior members; but they also I ofier a very considerable resistance to the outward flow of heat from the furnace, the

joints. being of relatively low heat conductivity. The joints or transverse divisions may be variously modified; thus they may comprise merely contacts such as are obtain able between juxtaposed graphite'memhers. It is preferred however to provide between the members in the direction of flow of the current a filling of material of relatively low heat conductivity, such as subdivided graphite or a graphitic ceme nt, In this figure 9 represents the furnace charge in contact with the terminal and resting upon a suitable refractory fill 10, the nature of which will depend upon the character of the charge. This fill is carried by the concrete or firebrick base 11 of the furnace, which may be provided with transverse; fines 12 for the circulation of air. The terminal 1 is illustrated as mounted in' a concrete furnace head 13, and is supported atitsinner end by a wall 14 of firebrick or other refractory which may consist of agglomerated carbon or graphite. The terminal may however be assembled as described with reference to Fig. 1 or in any other suitable manner. The charge is illustrated by Way of example as comprising carbon electrodes 17 to be'graphitized, these being arranged in piles separated by a granular material 18 of relatively low electrical conductivity, as granular carbon. *The charge as shown extends laterally beyond the terminals, and in order that the sectional area of the core may not be unduly increased, the articles comprising the charge are arranged in comparatively low piles as shown. If a charge of this form t the charge.

were arranged indirect contact Wllll the terminal an unequal heating of the latter Would result, an excessive proportion of the current being carried by the lower portion of the terminal or that in direct contact with It is necessary therefore to efiect a proper current distribution through the terminal, and this is accomplishedby the provision of so-called extension heads,

comprising in the form shown a series of graphite or carbon plates or bars coiiistituting a head 19, the members of which are'in electrically conductive relation with each other," as for example through .a graphitic cement 20. This head 19. is in contact with the charge and as illustrated extends to the full width of the charge and to the full height of the terminal and serves therefore to distribute the currentbetween the terminal and the char e. The head19 should he in efiective electrlcal COIltiLCt/Wlilh the terminal: such contact may be rovided in nu merous ways, as for example y an interposed filling of granular or subdivided grahite or a graphltic cement 21, retained by lateral supports consisting of carbon bars .22. Ub-

" viouslythe head 19 may comprise a single plate or block of aphite or carbon, or plates or blocks vertically disposed, it being essential only that the head be adapted to perform its function of properly distributing the current between the terminal and the charge. In addition to this functionrit e1"- forms the further. function of very e feet ively checkingmhe loss of heat by conducftion between the charge" and the terminal,

by virtue of the relatively high heat resist ance of the joint or connection 21. vThe,

v terminal, 7

blocks 19 are laterally in excellent electrical contact, and are of sutlicient size and thickness effectively to distribute the current.

I claim:

1. In an electric furnace, a terminal comprising a plurality of graphite members assembled in electrical connection, one or more of said members divided transversely of the current path.

2. In an electric furnace, a terminal comprising graphite members spaced in the direction of the current flow, and an interposed electrically conductive material of relatively low heat-conductivity.

3. In an electric furnace, a terminal. comprising graphite members spaced in the direction of the current flow, and an interposed filling of granular, electrically conductive material of relatively low heat-conductivity.

4. In an electric furnace, a terminal comprising graphite members spaced in the direction of the current flow, and an interposed filling of graphite in subdivided form.

5. In an electric furnace, a terminal comprising a plurality 'of parallel, electrically conductive members, assembled in close proximity and in electrically conductive relation to each other, one or more of said members divided transversely to the current path.

6. In an electric furnace, a terminal comprising a plurality of parallel electrically conductive members, assembled in close proximity and in electrically conductive relation.

to each other, one or more of said membersdivided transversely to the current path, and a filling of electrically conductive material between the ends of said members.

7. In an electric furnace, a terminal comprising graphite members spaced in the direction of current flow, and an interposed filling of electrically conductive material of relatively low heat-conductivity.

8. In an electric furnace, a terminal comprising graphite members spaced in the direction of current flow, and an interposed granular filling of electrically conductive material of relatively low heat-conductivity.

9. In an electric furnace, a terminal comprising solid members spaced in the direction of current flow, and an interposed filling of graphite in subdivided form- 10.. In an electric furnace, an extension head adapted for contact with the charge, a

terminal spaced from said head, and an electrically conductive filling of relatively low heat conductivity between said head and terminal. V I

11. Inan electric furnace,.an extension head adapted for contact with the charge,,a

terminal spaced from said head and difiering therefrom m'cross-section, and an elec-- trlcally conductive filling of relatively low heat conductivity' between said head and 12. In an electric furnace, an extension trically conductive section of relatively low head adapted for contact with the charge, heat-conductivity. 10 a graphite terminal spaced from said head, In testimony whereof, I afiix my signature and an electrically conductive filling ofrelain presence of two witnesses.

tively low heat-conductivity between said EBEN C. SPEIDEN. head and terminal. Witnesses: 13. In an electric furnace a graphite elec- WM. ACHESON SMITH,

trode having intermediate its ends an elec- ORRIN E. DUNLOP. 

